In the conventional colloid mills used in the fields of medical, cosmetic, dope, fine chemical industry and food processing etc., which are either conical-structured or disc-structured, the milling movements are small due to the limitation of the size of the mill tool. In order to achieve a super-fine grinding of a material, the equipment is usually of bulky structure. Not only are the manufacturing processes of the rotating and stationary mill bodies thereof complicated and costly, but also the motor has to run at very high speed, generally around 8000 rounds per minute, resulting in a loud noise during operation and a large consumption of power.
In the prior art domestic soybean milk maker, in order to achieve miniaturization, the grinding device is driven by a high-speed motor so that the crushing blades hit and crush the beans in filter gauze, with soybean milk filtered through the gauze and then boiled for drinking. Notable disadvantages thereof are: requirement of high rotation speed of the blades, large noise caused during operation, a low production rate of soybean milk, small regulating range of soybean milk concentration and quantity, and difficulty in gauze cleaning. As disclosed in CN2273965Y, “an automatic cycle mini soybean-milk maker of assembled type”, the grinding device thereof comprises a stator (i.e. a stationary grinder) and a rotor (i.e. a rotary grinder). The inventor believes that both the design and manufacture of the stator and the rotor are complicated and difficult, and it is impossible to obtain an integrated structure under conventional processes and technology, thus an assembled arrangement is employed for the stator and rotor, which results in a large number of mill parts, huge labor in assembling, and a high failure rate. Its operation principle is that material is pulled and pushed and thus crushed and ground by a cyclic force caused by the high-speed relative motion between the assembled stator and rotor, so that the material “escapes with high speed from the lower annular gap after being ground”. Thus, the high rotation speed also brings about a disadvantage of large noises.